A Provably Secure Threshold Ring Signature Scheme in Certificateless Cryptography

Ring signature is a kind of group-oriented signature. It allows a member of a group to sign messages on behalf of the group without revealing his/her identity. Certificateless public key cryptography was first introduced by Al-Riyami and Paterson at Asiacrypt 2003. In certificateless cryptography, it does not require the use of certificates to guarantee the authenticity of users' public keys. Meanwhile, certificateless cryptography does not have the key escrow problem, which seems to be inherent in the identity-based cryptography. In this paper, we introduce the notion of thresholdring signature into certificateless public key cryptography and propose a concrete certificateless threshold ring signature (CLT-Ring) scheme. The security models of certificateless threshold ring signature are also formalized. The new scheme is provably secure in the random oracle model.